Fluid cooling system

ABSTRACT

A fluid cooling system for an engine ( 101 ). The fluid cooling system comprises a junction ( 105 ), the junction comprising: a primary duct ( 102 ) suitable for conveying fluid into the junction; and a secondary duct ( 103 ) and a tertiary duct ( 104 ), the secondary and tertiary ducts being in fluid communication with the primary duct and being suitable for conveying fluid out of the junction. The secondary duct is arranged at a substantially oblique angle to the primary duct at the point at which the secondary duct meets the primary duct, and the tertiary duct is arranged at a substantially acute angle to the primary duct at the point at which the tertiary duct meets the primary duct.

TECHNICAL FIELD

This invention relates to a fluid cooling system for an engine, and toan engine and a vehicle comprising the same.

BACKGROUND

In order to prevent mechanical wear, engines will frequently make use oflubricants. The lubricants are interspersed between the moving parts ofthe engine in order that the parts can move more smoothly with respectto one another. The viscosity of the lubricants in an engine will varywith temperature, and usually the lubricants are chosen such that theywill perform well at the engine's typical operating temperature.However, for an engine which generates a significant amount of heat,such as an internal combustion engine, the engine will typically beginat an ambient temperature before rising to its typical operatingtemperature as the engine generates heat. Therefore there is a periodwhen the engine is started during which the lubricants within the engineare beneath their optimum operating temperature. For this reason it isoften desirable to allow components such as pistons and cylinders toheat up as quickly as possible when the engine is started, in order toensure that the lubricating oils within the pistons are as effective aspossible.

However, pistons and cylinders are also at risk of becoming too hot. Inparticular, the components contained at the head of the cylinder such asspark plugs and sensing apparatus are often very sensitive to beingoverheated. Therefore cylinders in modern engines are provided with anouter shell, or jacket, which is filled with a fluid, typically water.These water jackets provide cooling as the heat from the piston and thecylinder is absorbed by the water. The warmed water is then pumped outof the jacket and replaced with colder water to absorb more heat.

However, during engine start up, the jacket is still full of water, andas such the jacket tends to absorb heat, slowing the warming of thepiston and the cylinder, and therefore slowing the warming of thelubricant and reducing the efficiency of the lubricant shortly after theengine is started. This effect is worsened if cooler water is allowed toflow into the jacket during the warming up period.

It is important therefore to provide a water jacket that can provideeffective cooling for the vehicle while also minimising heat loss duringthe early stages after the internal combustion engine is started.

SUMMARY OF THE INVENTION

In accordance with an aspect of the present invention there is provideda fluid cooling system for an engine. The fluid cooling system comprisesa first cooling jacket, a second cooling jacket and a junction, thejunction comprising: a primary duct suitable for conveying fluid intothe junction; and a secondary duct and a tertiary duct, the secondaryand tertiary ducts being in fluid communication with the primary ductand being suitable for conveying fluid out of the junction. Thesecondary duct is in further fluid communication with the first coolingjacket and the tertiary duct is in further fluid communication with thesecond cooling jacket. The secondary duct is arranged at a substantiallyoblique angle to the primary duct at the point at which the secondaryduct meets the primary duct, and the tertiary duct is arranged at asubstantially acute angle to the primary duct at the point at which thetertiary duct meets the primary duct.

In this way a junction is provided in which fluid is able to traveleasily from the primary duct into the secondary duct, but in which fluidtravelling into the tertiary duct encounters a greater resistance due tothe acute change of direction which the fluid must undergo. As such,more fluid will tend to flow through the secondary duct than thetertiary duct. This difference can be provided based solely on the shapeand relationship of the ducts, without the need for complicated valvesystems which may be subject to mechanical failure after repeated use.As such, when fluid is flowing under pressure through the junction, forexample because it is being pumped, more fluid will tend to be suppliedto the first cooling jacket, through the secondary duct, than will besupplied to the second cooling jacket, through the tertiary duct. Thelarger quantities of fluid flowing through the first cooling jacket willtend to cause the first cooling jacket to absorb more heat than thesecond cooling jacket, all other factors being equal. In use, therefore,an engine component which is contained inside the first cooling jacketwill tend to have more heat energy removed than an engine componentwhich is contained inside the second cooling jacket.

By substantially oblique it is meant that fluid flowing from the primaryduct into the secondary duct will undergo a translation in direction oftravel which is less than ninety degrees. It may be that fluid flowingfrom the primary duct into the secondary duct will undergo a translationin direction of travel which is less than thirty degrees. Bysubstantially acute it is meant that fluid flowing from the primary ductinto the tertiary duct will undergo a translation in direction of travelwhich is greater than ninety degrees. It may be that fluid flowing fromthe primary duct into the tertiary duct will undergo a translation indirection of travel which is greater than one hundred and fifty degrees.It may be that the tertiary duct is arranged with respect to the primaryand secondary ducts, for example by virtue of required translation indirection of travel of fluid and/or by virtue of size, so that amajority of the flow from the primary duct enters the secondary duct.

Typically, the primary and secondary ducts form a single duct. Wherethis is the case, it may be that a hole is bored in the single duct thatforms the primary and secondary ducts, with the tertiary duct beingattached to the primary and secondary ducts at the hole in order to formthe junction.

It may be that the engine is an internal combustion engine. However acooling system according to the invention may be used with any engine orsystem which requires cooling, particularly where such engine or systemrequires or would benefit from cooling at least at two differing rates.

Where the engine is an internal combustion engine, it may be a pistondriven internal combustion engine. Where this is the case, the fluidcooling system may comprise a first water jacket for a piston cylinderhead, the secondary duct being in fluid communication with the firstwater jacket. The fluid cooling system may comprise a second waterjacket for a piston cylinder, the tertiary duct being in fluidcommunication with the second water jacket. Typically, such a secondwater jacket is intended to cool a section of the piston cylinderthrough which the piston travels.

It may be that the tertiary duct is connected to a lower portion of thesecond water jacket. Lower here means lower with respect to gravity. Itmay be that the tertiary duct is connected to the bottom half of thesecond water jacket. It may be that the tertiary duct is connected tothe bottom of the second water jacket, or it may be that the tertiaryduct is connected adjacent the bottom of the second water jacket.

Typically, the fluid cooling system further comprises a pump, the pumpbeing in fluid communication with the primary duct and suitable forpumping fluid into the junction. It may be that the pump is in fluidcommunication with at least one of the first and second water jacketsand is suitable for pumping fluid out of the first and/or second waterjacket.

Alternatively, the fluid may be moved around the system using some othermethod, for example by relying upon convection currents.

It may be that the fluid comprises water. Typically, such fluid isprimarily water by mass. The fluid may comprise other fluids such asadditives intended to lower the freezing point of the water.

It may be that the secondary duct has a bore substantially the same asthe bore of the primary duct. It will be appreciated that this meansthat it has the same cross-sectional area. It may be that the tertiaryduct has a bore smaller than the bore of the secondary duct. It may bethat the tertiary duct has a bore smaller than the bore of the primaryduct. A smaller cross sectional area in the bore of the tertiary ducthelps to further reduce the flow of fluid through the tertiary duct ascompared to the secondary duct.

It may be that the second cooling jacket comprises a heater. The heatermay be located inside the second cooling jacket. Alternatively, theheater may be located adjacent to the second cooling jacket. The heatermay be an electrical heater.

The second cooling jacket may comprise a first compartment and a secondcompartment, the second compartment being joined to the firstcompartment by one or more capillaries or ducts, the tertiary duct beingconnected to the first compartment. Where a heater is provided, theheater will typically be located in or next to the second compartment,such that the heater can heat fluid within the second compartment.

It may be that the fluid cooling system has a typical orientation foruse, wherein the tertiary duct reaches the second cooling jacket at apoint substantially lower than the junction when the fluid coolingsystem is in the typical orientation.

In an aspect, the invention provides a method of cooling an engine, themethod comprising:

-   -   providing a fluid cooling system as described above;    -   attaching the fluid cooling system to the engine; and    -   pumping fluid around the fluid cooling system.

In an aspect, the invention provides an engine which comprises a fluidcooling system as described above. In an, the invention provides avehicle which comprises an engine, the engine comprising a fluid coolingsystem as described above.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the invention are further described hereinafterwith reference to the accompanying drawings, in which:

FIGS. 1 shows a diagram of a first cooling system according to theinvention;

FIGS. 2 and 3 show a second cooling system; and

FIGS. 4, 5 and 6 show a third cooling system.

DETAILED DESCRIPTION

FIG. 1 shows a diagram of a first cooling system 101 according to theinvention. The cooling system 101 is intended for use with a pistondriven internal combustion engine (not shown) and comprises a firstprimary duct 102, a first secondary duct 103 and a first tertiary duct104, which are all connected at a junction 105. FIG. 1 shows the firstcooling system in substantially the same orientation in which it wouldbe installed in a vehicle, with the upper parts of the diagramrepresenting those parts which would be higher with respect to gravityin a vehicle fitted with the first cooling system 101.

The first secondary duct is further connected to a first water jacket106, which is intended to fit around and provide cooling for a pistoncylinder head (not shown). The first water jacket 106 is provided with afirst outflow 107.

The first tertiary duct 104 is further connected to a second waterjacket 108 which is intended to fit around and provide cooling for thesection of a piston cylinder through which a piston head travels (alsonot shown). The second water jacket 108 is provided with a secondoutflow 109, which comprises a valve 110.

In use, water is pumped around the first cooling system 101 in thedirections shown by the arrows 111, so that the water will absorb excessheat from the piston cylinder and the piston cylinder head. The waterthen travels via the first and second outflows 107, 109, to a radiatorwhere the water is allowed to cool before being pumped through the firstcooling system 101 again. This prevents the piston cylinder and thepiston cylinder head from becoming hot enough to damage the componentscontained therein.

However when the engine is cold, which typically occurs immediatelyfollowing an engine start, it may be advantageous to encourage rapidwarming of the piston cylinder. When the engine is cold, therefore, thevalve 110 may be closed to prevent outflow of water from the secondwater jacket 108 through the second outflow 109. Hence water in thesecond water jacket 108 will tend to be trapped there. The water trappedin the second water jacket 108 then absorbs heat from the pistoncylinder. This still slows the rate at which the piston cylinder willheat up, but since the warmed water is retained next to the pistoncylinder, the piston cylinder is able to heat up faster than would bethe case if the valve 110 was open.

Typically, even immediately after start up it is still necessary to pumpwater through the first primary and first secondary ducts 102, 103 tothe first water jacket 106. This is because the cylinder head tends togenerate a lot of heat very rapidly, and also contains equipment whichis sensitive to overheating.

The first tertiary duct 104 and the second water jacket 108 are designedto reduce syphoning of water into and out of the second water jacket108, and so more effectively trap water, particularly warmer water, inthe second water jacket 108.

Firstly, the first tertiary duct 104 is connected to the junction 105 atan acute angle to the first primary duct 102. As a result, the flow ofwater through the first tertiary duct 104, when such a flow occurs, isalso at an acute angle to the flow of water through the first primaryduct 102. Therefore water flowing through the first primary duct 102 tothe junction 105 must alter its course substantially in order to enterthe first tertiary duct 104, as indicated by the arrows 111. Incontrast, the first secondary duct 103 is arranged as a continuation ofthe first primary duct 102, so that water flowing from the first primaryduct 102 into the first secondary duct 103 does not need to alter itscourse. The inventor has found that this relationship between the ductstends to reduce the amount of water which flows into the second waterjacket 108, in particular when the valve 110 is closed.

Secondly, the first tertiary duct 104 is connected to the bottom of thesecond water jacket 108. As the water in the second water jacket 108absorbs heat from the piston cylinder, the hottest water will tend torise to the top of the second water jacket 108, which is also the top ofthe diagram shown in FIG. 1. As such, the hottest water is trapped atthe opposite end of the second water jacket 108 from the fluidconnection with the first tertiary duct 104. This tends to preventthermo-syphoning of water from the second water jacket 108. Suchthermo-syphoning may be undesirable in a circumstance in which a rapidinitial warming up of the piston cylinder is preferable.

Once the piston cylinder has achieved a desired temperature, the valve110 can be opened to allow a flow of water out of the second waterjacket 108. Some of the colder water being pumped through the firstprimary duct 102 will then travel down the first tertiary duct 104 andinto the second water jacket 108, where it can absorb heat from thepiston cylinder and so help to regulate the temperature of the pistoncylinder.

However, even once the valve 110 is open the water flow through thefirst tertiary duct 104 will still be less than the water flow throughthe first secondary duct 103, due to the acute angle between the firsttertiary duct 104 and the first primary duct 102. As such, more coolingwater is delivered to the first water jacket 106 than to the secondwater jacket 108. As such the piston cylinder loses less heat than, andcan be maintained at a higher temperature than the piston cylinder head.The precise relationship between the water pumped through the secondaryand tertiary ducts can be controlled by adjusting the angle of thetertiary duct relative to the primary duct.

The first tertiary duct 104 is also narrower than the first secondaryduct 103, in that it has a bore with a smaller cross-sectional area.This has the effect of further restricting the water flow into thesecond water jacket 108. The relationship between the water pumpedthrough the first secondary duct 103 and the first tertiary duct 104 cantherefore also be controlled by changing the bore of the tertiary ductrelative to the bore of the secondary duct.

FIGS. 2 and 3 show a section of a second cooling system 201 according tothe invention. Like components with the first cooling system 101 arenumbered with like numerals, except in the two hundreds range ratherthan the one hundreds range. The second cooling system 201 comprises asecond primary duct 202, a second secondary duct 203 and a secondtertiary duct 204, which are arranged in a similar manner to the ductsin FIG. 1. Water flows through the ducts as indicated by the arrows 211in FIG. 2. The second secondary duct 203 is connected to a third waterjacket for a piston cylinder head (not shown). The second tertiary duct204 is connected to a fourth water jacket 208 which is intended to fitaround several piston cylinders.

As with the first cooling system 101, the second tertiary duct isconnected to the bottom of the fourth water jacket to reduce thermalsyphoning. The second tertiary duct 204 is also arranged at an acuteangle to the second primary duct 202 in order to reduce water flow fromthe second primary duct 202 into the second tertiary duct 204.

FIGS. 4 and 5 show a section of a third cooling system 301 according tothe invention. Like components with the first cooling system 101 arenumbered with like numerals, except in the three hundreds range ratherthan the one hundreds range. The third cooling system 301 comprises athird primary duct 302, a third secondary duct 303 and a third tertiaryduct 304, which are arranged in a similar manner to the ducts in FIG. 1and FIG. 2. Water flows through the pipes as indicated by the arrows 311in FIG. 4. The third secondary duct 303 is connected to a fifth waterjacket for a piston cylinder head (not shown). The third tertiary duct304 splits into two quaternary ducts 312, and each quaternary duct 312is connected to a sixth water jacket 308 which is intended to fit aroundfour piston cylinders.

FIG. 6 shows a plan view of the third cooling system 301 in which theconnection between the quaternary ducts 312 and the sixth water jacket308 can be seen. Water flows in and out of the sixth water jacket 308 asindicated by the arrows 311 in FIG. 6.

As with previous embodiments, the quaternary ducts 312 are connected tothe bottom of the sixth water jacket 308 to reduce thermal syphoning.The third tertiary duct 304 is also arranged at an acute angle to thesecond primary duct 302 in order to reduce water flow from the thirdprimary duct 302 into the third tertiary duct 304.

In an embodiment, one of the quaternary ducts 312 may be sealed, so thatno water may flow through it. Water can then still reach the sixth waterjacket 308 through the open quaternary duct 312, while the sealedquaternary duct 312 serves only to support the water cooling system bymaintaining the spatial relationship between the sixth water jacket 308and the ducts 302, 303, 304, 312.

FIG. 7 shows a fourth cooling system according to the invention 401.Like components with the first cooling system 101 are numbered with likenumerals, except in the four hundreds range rather than the one hundredsrange. The fourth cooling system 401 operates in a similar way to thefirst cooling system 101, with the same arrangement of ducts to conductwater into and out of water jackets 406, 408.

In extreme cold conditions, it can become very difficult to start aninternal combustion engine. In particular, at -40 degrees centigrade andbelow, a petrol engine may be unable to start. Therefore it can behelpful to provide further assistance to an engine in these conditions.

The fourth cooling system 401 comprises a seventh water jacket 406 andan eighth water jacket 408. The eighth water jacket 408 comprises afirst compartment 413 and a second compartment 414. The first and secondcompartments 413, 414 are joined by several capillaries 415, such thatfluid can flow between the first and second compartments by passingthrough the capillaries. When installed in an engine, the firstcompartment 413, second compartment 414 and the capillaries 415 enclosea piston cylinder (not shown) as is described above with reference toFIG. 1.

The fourth cooling system 401 further comprises a heating element 416,which is located in the second compartment 414. The heating element 416comprises a conductor which, when provided with an electrical current,produces heat. The heating element 416 is electrically insulated fromthe fluids in the heating element 416 in order to prevent the elementdischarging into the cooling fluid inside the eighth water jacket 408.

At very low ambient temperatures such as -40 degrees centigrade,therefore, the heating element 416 can be used to help heat fluid in theeighth water jacket 408. The heated fluid then in turn heats the pistoncylinder, and so assists the engine in starting.

Fluid heated by the heating element 416 tends to rise as indicated byarrow 417. The fluid heated by the heating element 416 can also flowfrom the second compartment 414 into the first compartment 413 throughthe capillaries 415 as indicated by the arrow 418. However the smallsize of the capillaries 415 means that the transit of liquid between thetwo compartments is slow, especially when the valve 410 is closed sothat there is no overall flow of fluid through the eighth water jacket408. Hence the heated fluid tends to accumulate at the top of the secondcompartment 414, well away from the fourth tertiary duct 404. This tendsto reduce thermal syphoning of warm fluid out of the eighth water jacket408. As such the location of the fourth tertiary duct 404 again helps tomaintain and increase the temperature of the piston cylinder as isdiscussed above with reference to other embodiments.

Throughout the description and claims of this specification, the words“comprise” and “contain” and variations of them mean “including but notlimited to”, and they are not intended to (and do not) exclude othermoieties, additives, components, integers or steps.

Throughout the description and claims of this specification, thesingular encompasses the plural unless the context otherwise requires.In particular, where the indefinite article is used, the specificationis to be understood as contemplating plurality as well as singularity,unless the context requires otherwise.

Features, integers, characteristics, compounds, chemical moieties orgroups described in conjunction with a particular aspect, embodiment orexample of the invention are to be understood to be applicable to anyother aspect, embodiment or example described herein unless incompatibletherewith. All of the features disclosed in this specification(including any accompanying claims, abstract and drawings), and/or allof the steps of any method or process so disclosed, may be combined inany combination, except combinations where at least some of suchfeatures and/or steps are mutually exclusive. The invention is notrestricted to the details of any foregoing embodiments. The inventionextends to any novel one, or any novel combination, of the featuresdisclosed in this specification (including any accompanying claims,abstract and drawings), or to any novel one, or any novel combination,of the steps of any method or process so disclosed.

1-14. (canceled)
 15. A fluid cooling system for an engine, the fluidcooling system comprising a first cooling jacket suitable for cooling atleast part of a piston cylinder head, a second cooling jacket suitablefor cooling at least part of a piston cylinder and a junction, thejunction comprising: a primary duct suitable for conveying fluid intothe junction; and a secondary duct and a tertiary duct, the secondaryand tertiary ducts being in fluid communication with the primary ductand being suitable for conveying fluid out of the junction, thesecondary duct being in further fluid communication with the firstcooling jacket and the tertiary duct being in further fluidcommunication with the second cooling jacket, wherein the secondary ductis arranged at a substantially obtuse angle to the primary duct at thepoint at which the secondary duct meets the primary duct, and thetertiary duct is arranged at a substantially acute angle to the primaryduct at the point at which the tertiary duct meets the primary duct. 16.A fluid cooling system as claimed in claim 15, wherein the primary andsecondary ducts form a single duct.
 17. A fluid cooling system asclaimed in claim 15, wherein the engine is an internal combustionengine.
 18. A fluid cooling system as claimed in claim 15, wherein thetertiary duct is connected to a lower portion of the second coolingjacket.
 19. A fluid cooling system as claimed in claim 15, comprising apump suitable for pumping fluid into the junction.
 20. A fluid coolingsystem as claimed in claim 15, wherein the fluid comprises water.
 21. Afluid cooling system as claimed in claim 15, wherein the secondary ducthas a bore substantially the same as a bore of the primary duct.
 22. Afluid cooling system as claimed in claim 15, wherein the tertiary ducthas a bore smaller than a bore of the secondary duct.
 23. A fluidcooling system as claimed in claim 15, wherein the second cooling jacketcomprises a heater.
 24. A fluid cooling system as claimed in claim 15,comprising an exit duct from the second cooling jacket and a valve tocontrol a flow of fluid from the second cooling jacket via the exitduct.
 25. A fluid cooling system as claimed in claim 15, the fluidcooling system having a typical orientation for use, wherein thetertiary duct reaches the second cooling jacket at a point substantiallylower than the junction when the fluid cooling system is in the typicalorientation.
 26. A method of cooling an engine, the method comprising:providing a fluid cooling system comprising a first cooling jacketsuitable for cooling at least part of a piston cylinder head, a secondcooling jacket suitable for cooling at least part of a piston cylinderand a junction, the junction comprising: a primary duct suitable forconveying fluid into the junction; and a secondary duct and a tertiaryduct, the secondary and tertiary ducts being in fluid communication withthe primary duct and being suitable for conveying fluid out of thejunction, the secondary duct being in further fluid communication withthe first cooling jacket and the tertiary duct being in further fluidcommunication with the second cooling jacket, wherein the secondary ductis arranged at a substantially obtuse angle to the primary duct at thepoint at which the secondary duct meets the primary duct, and thetertiary duct is arranged at a substantially acute angle to the primaryduct at the point at which the tertiary duct meets the primary duct;attaching the fluid cooling system to the engine; and pumping fluidaround the fluid cooling system.
 27. An engine comprising a fluidcooling system as claimed in claim
 15. 28. A vehicle comprising anengine according to claim 27.